Simulations of the Milky Way's central molecular zone -- II. Star formation

The Milky Way's central molecular zone (CMZ) has emerged in recent years as a unique laboratory for the study of star formation. Here we use the simulations presented in Tress et al. 2020 to investigate star formation in the CMZ. These simulations resolve the structure of the interstellar medium at sub-parsec resolution while also including the large-scale flow in which the CMZ is embedded. Our main findings are as follows. (1) While most of the star formation happens in the CMZ ring at $R\gtrsim100 {\, \rm pc}$, a significant amount also occurs closer to SgrA* at $R \lesssim 10{\, \rm pc}$. (2) Most of the star formation in the CMZ happens downstream of the apocentres, consistent with the "pearls-on-a-string" scenario, and in contrast to the notion that an absolute evolutionary timeline of star formation is triggered by pericentre passage. (3) Within the timescale of our simulations ($\sim100$ Myr), the depletion time of the CMZ is constant within a factor of $\sim2$. This suggests that variations in the star formation rate are primarily driven by variations in the mass of the CMZ, caused for example by AGN feedback or externally-induced changes in the bar-driven inflow rate, and not by variations in the depletion time. (4) We study the trajectories of newly born stars in our simulations. We find several examples that have age and 3D velocity compatible with those of the Arches and Quintuplet clusters. Our simulations suggest that these prominent clusters originated near the collision sites where the bar-driven inflow accretes onto the CMZ, at symmetrical locations with respect to the Galactic centre, and that they have already decoupled from the gas in which they were born.Comment: Accepted for publication in MNRAS. Movies of the simulations can be found at: https://www.youtube.com/channel/UCwnzfO-xLxzRDz9XsexfPo

Crop Updates 2005 - Farming Systems

This session covers forty four papers from different authors: PLENARY 1. 2005 Outlook, David Stephens and Nicola Telcik, Department of Agriculture FERTILITY AND NUTRITION 2. The effect of higher nitrogen fertiliser prices on rotation and fertiliser strategies in cropping systems, Ross Kingwell, Department of Agriculture and University of Western Australia 3. Stubble management: The short and long term implications for crop nutrition and soil fertility, Wayne Pluske, Nutrient Management Systems and Bill Bowden, Department of Agriculture 4. Stubble management: The pros and cons of different methods, Bill Bowden, Department of Agriculture, Western Australia and Mike Collins, WANTFA 5. Effect of stubble burning and seasonality on microbial processes and nutrient recycling, Frances Hoyle, The University of Western Australia 6. Soil biology and crop production in Western Australian farming systems, D.V. Murphy, N. Milton, M. Osman, F.C. Hoyle, L.K Abbott, W.R. Cookson and S. Darmawanto, The University of Western Australia 7. Urea is as effective as CAN when no rain for 10 days, Bill Crabtree, Crabtree Agricultural Consulting 8. Fertiliser (N,P,S,K) and lime requirements for wheat production in the Merredin district, Geoff Anderson, Department of Agriculture and Darren Kidson, Summit Fertilizers 9. Trace element applications: Up-front verses foliar? Bill Bowden and Ross Brennan, Department of Agriculture 10. Fertcare®, Environmental Product Stewardship and Advisor Standards for thee Fertiliser Industry, Nick Drew, Fertilizer Industry Federation of Australia (FIFA) SOIL AND LAND MANAGEMENT 11. Species response to row spacing, density and nutrition, Bill Bowden, Craig Scanlan, Lisa Sherriff, Bob French and Reg Lunt, Department of Agriculture 12. Investigation into the influence of row orientation in lupin crops, Jeff Russell, Department of Agriculture and Angie Roe, Farm Focus Consultants 13. Deriving variable rate management zones for crops, Ian Maling, Silverfox Solutions and Matthew Adams, DLI 14. In a world of Precision Agriculture, weigh trailers are not passé, Jeff Russell, Department of Agriculture 15. Cover crop management to combat ryegrass resistance and improve yields, Jeff Russell, Department of Agriculture and Angie Roe, Farm Focus Consultants 16. ARGT home page, the place to find information on annual ryegrass toxicity on the web, Dr George Yan, BART Pty Ltd 17. Shallow leading tine (SLT) ripper significantly reduces draft force, improves soil tilth and allows even distribution of subsoil ameliorants, Mohammad Hamza, Glen Riethmuller and Wal Anderson, Department of Agriculture PASTURE ANS SUMMER CROP SYSTEMS 18. New annual pasture legumes for Mediteranean farming systems, Angelo Loi, Phil Nichols, Clinton Revell and David Ferris, Department of Agriculture 19. How sustainable are phase rotations with Lucerne? Phil Ward, CSIRO Plant Industry 20. Management practicalities of summer cropping, Andrea Hills and Sally-Anne Penny, Department of Agriculture 21. Rainfall zone determines the effect of summer crops on winter yields, Andrea Hills, Sally-Anne Penny and David Hall, Department of Agriculture 22. Summer crops and water use, Andrea Hills, Sally-Anne Penny and David Hall, Department of Agriculture, and Michael Robertson and Don Gaydon, CSIRO Brisbane 23. Risk analysis of sorgum cropping, Andrea Hills and Sally-Anne Penny, Department of Agriculture, and Dr Michael Robertson and Don Gaydon, CSIRO Brisbane FARMER DECISION SUPPORT AND ADOPTION 24. Variety release and End Point Royalties – a new system? Tress Walmsley, Department of Agriculture 25. Farming system analaysis using the STEP Tool, Caroline Peek and Megan Abrahams, Department of Agriculture 26. The Leakage Calculator: A simple tool for groundwater recharge assessment, Paul Raper, Department of Agriculture 27. The cost of Salinity Calculator – your tool to assessing the profitability of salinity management options, Richard O’Donnell and Trevor Lacey, Department of Agriculture 28. Climate decision support tools, Meredith Fairbanks and David Tennant, Department of Agriculture 29. Horses for courses – using the best tools to manage climate risk, Cameron Weeks, Mingenew-Irwin Group/Planfarm and Richard Quinlan, Planfarm Agronomy 30. Use of seasonal outlook for making N decisions in Merredin, Meredith Fairbanks and Alexandra Edward, Department of Agriculture 31. Forecasts and profits, Benefits or bulldust? Chris Carter and Doug Hamilton, Department of Agriculture 32. A tool to estimate fixed and variable header and tractor depreciation costs, Peter Tozer, Department of Agriculture 33. Partners in grain: ‘Putting new faces in new places’, Renaye Horne, Department of Agriculture 34. Results from the Grower group Alliance, Tracey Gianatti, Grower Group Alliance 35. Local Farmer Group Network – farming systems research opportunities through local groups, Paul Carmody, Local Farmer Group Network GREENHOUSE GAS AND CLIMATE CHANGE 36. Changing rainfall patterns in the grainbelt, Ian Foster, Department of Agriculture 37. Vulnerability of broadscale agriculture to the impacts of climate change, Michele John, CSIRO (formerly Department of Agriculture) and Ross George, Department of Agriculture 38. Impacts of climate change on wheat yield at Merredin, Imma Farré and Ian Foster, Department of Agriculture 39. Climate change, land use suitability and water security, Ian Kininmonth, Dennis van Gool and Neil Coles, Department of Agriculture 40. Nitrous oxide emissions from cropping systems, Bill Porter, Department of Agriculture, Louise Barton, University of Western Australia 41. The potential of greenhouse sinks to underwrite improved land management in Western Australia, Richard Harper and Peter Ritson, CRC for Greenhouse Accounting and Forest Products Commission, Tony Beck, Tony Beck Consulting Services, Chris Mitchell and Michael Hill, CRC for Greenhouse Accounting 42. Removing uncertainty from greenhouse emissions, Fiona Barker-Reid, Will Gates, Ken Wilson and Rob Baigent, Department of Primary Industries - Victoria and CRC for Greenhouse Accounting (CRCGA), and Ian Galbally, Mick Meyer and Ian Weeks, CSIRO Atmospheric Research and CRCGA 43. Greenhouse in Agriculture Program (GIA), Traci Griffin, CRC for Greenhouse Accounting 44. Grains Greenhouse Accounting framework, D. Rodriguez, M. Probust, M. Meyers, D. Chen, A. Bennett, W. Strong, R. Nussey, I. Galbally and M. Howden CONTACT DETAILS FOR PRINCIPAL AUTHOR

Unusual Galactic H ii Regions at the Intersection of the Central Molecular Zone and the Far Dust Lane

Sgr E is a massive star formation complex found toward the Galactic center that consists of numerous discrete, compact H ii regions. It is located at the intersection between the central molecular zone (CMZ) and the far dust lane of the Galactic bar, similar to "hot spots" seen in external galaxies. Compared with other Galactic star formation complexes, the Sgr E complex is unusual because its H ii regions all have similar radio luminosities and angular extents, and they are deficient in ~10 μm emission from their photodissociation regions (PDRs). Our Green Bank Telescope radio recombination line observations increase the known membership of Sgr E to 19 H ii regions. There are 43 additional H ii region candidates in the direction of Sgr E, 26 of which are detected for the first time here using MeerKAT 1.28 GHz data. Therefore, the true H ii region population of Sgr E may number >60. Using APEX SEDIGISM $^{13}$CO 2 $\rightarrow$ 1 data we discover a 3.0 × 10$^5$ M_ \bigodot molecular cloud associated with Sgr E, but find few molecular or far-infrared concentrations at the locations of the Sgr E H ii regions. Comparison with simulations and an analysis of its radio continuum properties indicate that Sgr E formed upstream in the far dust lane of the Galactic bar a few million years ago and will overshoot the CMZ, crashing into the near dust lane. We propose that the unusual infrared properties of the Sgr E H ii regions are caused by their orbits about the Galactic center, which have possibly stripped their PDRs

Crop Updates 1999 - Cereals

This article covers sixty papers FOREWORD ACKNOWLEDGMENTS PLENARY PAPERS 1. Western Australia’s climate: trends and opportunities, Len W. Broadbridge, Director, Bureau of Meterorology 2. Managing seasonal variations in agriculture, Dr Doug Abrecht, Director, Dryland Research Institute, Merredin CROP ESTABLISHMENT 3. Soil management to prevent waterlogging on duplex soils in the Great Southern, D. Bakker, Greg Hamilton, Cliff Spann and Doug Rowe, Agriculture Western Australia 4. The influence of no-till and press wheels on crop production for heavy soils, Peter Fisher, Jennifer Bignell, Matthew Braimbridge, Greg Hamilton, Agriculture Western Australia NUTRITION 5. Fertiliser nitrogen, applied late, needs rain to increase grain nitrogen and protein levels in wheat, Bill Bowden1, Ross Brennan1, Reg Lunt1 and Senthold Asseng2 1 Agriculture Western Australia, 2 CSIRO 6. Canola upsets the nutrition of the next cereal crop? Bill Bowden1, Garren Knell1, Cherie Rowles 1, Simon Bedbrook\u27, Chris Gazey 1,Mike Bolland1, Ross Brennan 1, Lyn Abbott2, Zed Rengel2 and Wayne Pluske3, 1 Agriculture Western Australia, 2 UWA Soil Science, 3 CSBP 7. Comparisons between high analysis nitrogen sources, Erin Cahill, CSBP 8. Urea additives for reduced drilled urea toxicity for canola and wheat, Bill Crabtree, WANTFA 9. Fertiliser placement, Matthew Evans, CSBP 9. The profitability of variable rate nitrogen applications on wheat, Tim Nielsen, CSBP Technical Services DISEASE 10. Fungicide for wheat leaf disease: boon or bane? Jat Bhathal, Rob Loughman and D. Rasmussen, Plant Pathology, Agriculture Western Australia 11. Role of retained wheat stubbles in disease carryover in wheat/lupin rotations, Jat Bhathal and Rob Loughman, Plant Pathology, Agriculture Western Australia 12. Comparison of aerial and ground application of fungicide for lead disease control ion wheat, Jat Bhathal and Rob Loughman, Plant Pathology, Agriculture Western Australia 13. Bean yellow mosaic virus infection of alternative pasture legume species, Roger Jones, CRC for legumes in Mediterranean Agriculture and Agriculture Western Australia 14. Survey of cereal root nematodes in cropping soils in Western Australia, Sean Kelly1, Ian Riley2 and Robert Loughman1, 1 Agriculture Western Australia,2 University of Adelaide 15. Crop management options for root lesion nematode, Robert Loughman 1, Sharyn Taylor2, Vivien Vanstone 3, Ian Riley3 and Dominie Wright1, 1 Agriculture Western Australia, 2SARDI Plant Research Centre, Glen Osmond, South Australia 3 University of Adelaide, Glen Osmond, South Australia 16. Forecasting barley yellow dwarf risk in cereals, Debbie Thackray and Roger Jones, Agriculture Western Australia and CRC for Legumes in Mediterranean Agriculture 17. Managing barley yellow dwarf virus in cereal crops, Debbie Thackray, Roger Jones and Simon McKirdy, Agriculture Western Australia and CRC for Legumes in Mediterranean Agriculture 18. Broadacre diagnostic service, Dominie Wright, Agriculture Western Australia, AGWEST Plant Laboratories 19. Using twist fungus (Dilophospora alopecuri) to reduce the risk of annual ryegrass toxicity, Dr George Yan1 and Dr Ian Riley2, 1 Plant Research and Development Service, Agriculture Western Australia, 2 Applied and Molecular Ecology, Waite Campus, The University of Adelaide, South Australia NEW VARIETIES 20. New wheat and oat varieties for 1999, Robin Wilson, lain Barclay, Robyn Mclean, Dean Diepeveen, Robert Loughman, and Bill Lambe, Agriculture Western Australia 21. Performance in 1998 of recently released wheat varieties, Robin Wilson, lain Barclay, Robyn Mclean, Dean Diepeveen, Robert Loughman and Bill Lambe, Agriculture Western Australia WHEAT AGRONOMY 22. Increasing the noodle ‘strike rate’, Wal Anderson, Brenda Shackley and Mechelle Owen, Agriculture Western Australia, Quality Wheat CRC 23. Variety trials: wheat and barley, Peter Burgess, Lamond Burgess & Associates 24. South coast wheat variety farmer survey, Ben Curtis, Agriculture Western Australia 25. Residual effects of deep ripping, gypsum and nutrients on grain yields and soil properties, Mohammed A. Hamza and W.K. Anderson, Agriculture Western Australia 26. How to ensure durum wheat profitability! Jamie Henderson, Frank Boetel and Alfredo lmpiglia, Agriculture Western Australia 27. Agronomic evaluation of new wheat varieties for 1999 in the Northern Agricultural Region, Frances Hoyle, Agriculture Western Australia 28. The influence of on-farm management and variety of grain screening levels, Frances Hoyle, Agriculture Western Australia 29. Variety response of hard wheats to management, Darshan Sharma and Wal Anderson, Agriculture Western Australia BARLEY AND OATS 30. Studies into production of export oaten hay, Pierre Fievez, Pierre Fievez and Associates 31. Gairdner barley in the Central and Northern Regions, Blakely Paynter, Agriculture Western Australia 32. Improving milling oat quality, Glenn McDonald, Agriculture Western Australia 33. Gairdner barley in the Southern Region, Kevin Young, Agriculture Western Australia PASTURE 34. The herbicide tolerance of some annual pasture legumes, Andrew Blake, Agriculture Western Australia 35. Pasture systems for cropping rotations in the northern wheatbelt, Keith Devenish, Agriculture Western Australia 36. Perennial pastures reduce recharge and acidification, Perry Dolling, Agriculture Western Australia 37. It’s time to include Lucerne in the pasture-crop system, Roy Latta 1, Lisa-Jane Blacklow2 and Chris Matthews 1,1 Agriculture Western Australia, 2 University of Western Australia, 38. New alternative pasture legume for fine textured soils, Angelo Loi, Brad Nutt and Rochelle McRobb, National Australian Pasture Legumes Improvement Program (NAPLIP) and Centre for Legumes in Mediterranean Agriculture (CLIMA) 39. Increasing pasture productivity on acid wodjil soils, Brad Nutt, David Webb and Andrew McRobb, Centre for Legumes in Mediterranean Agriculture (CLIMA) 40. Annual legume pasture species now available for use in cropping systems. Clinton Revell, Agriculture Western Australia 41. Herbicide and cultural management of Cadiz serradella in ‘phase’ pastures, Clinton Revell, Agriculture Western Australia 42. Spring spraying for redlegged earth mite, James Ridsdill-Smith and Celia Pavri, CSIRO Entomology and CLIMA 43. Water use and water extraction by recently developed pasture legume species and cultivars, David Tennant1, Darryl McClements2, Ross Thompson 1 and Mike Ewing2, 1 Natural Resource Management Services, Soil Management, 2 Plant Research and Development, Pasture Sciences 44. Death knell to doublegees? Tim Woodburn· and Paul Yeoh, CSIRO Entomology/CRC Weed Management Systems, Floreat LIMING 45. Calculated lime requirements for rotations, James Fisher1, Art Diggle 1•2 and Bill Bowden 1•2, 1 Centre for Legumes in Mediterranean Agriculture 2 Agriculture Western Australia 46. The RH lime reactivity test and RH of typical WA limes, Mark Whitten and Andrew Rate, Soil Science and Plant Nutrition, University of Western Australia YIELD MAPPING 47. Benchmarking target yields for wheat, Senthold Asseng 1, Bill Bowden2 and Paul Carlile3, 1 CSIRO Plant Industry, 2 Agriculture Western Australia, 3 UWA 48. Getting the most information from farm scale trial, Ed Blanchard, Agricultural Engineering and Precision Farming Consultant, Merredin, WA 49. Measuring nutrient changes using yield maps, Ed Blanchard, Agricultural engineering and precision farming consultant; Precision Farming Demonstration Project Coordinator for the Kondinin Group, Merredin WA BREEDING 50. Crop improvement royalties – investing in the future, Bevan Buirchell and Dean Diepeveen, Agriculture Western Australia 51. Screening cereals for genotypic variation in phosphorus efficiency, Lorraine Osborne and Zed Rengel, Soil Science and Plant Nutrition, University of Western Australia ON FARM TESTING 52. Test as you grow pays dividends, John Blake, Tress Walmsley, Terry Piper, Wal Anderson, Dean Diepeveen, Cameron Weeks, Michael Dodd, Amanda Falconer, Caroline Peek, Glenn Adam, Agriculture Western Australia 53. How useful is on-farm testing, Camray Gethin 1, Richard Guinness2, Simon Bedbrook1, Dean Diepeveen4, 1 TopCrop Development Officer, Agriculture Western Australia, 2 Farmer, Kunjin TopCrop Group, Corrigin, 3 Agricultural Consultant, Farmanco, York, 4 CVT service, Crop Industries, Agriculture Western Australia, ECONOMICS 54. The impact of farm practices on sustainability costs of rotations, Pierre Fievez, Pierre Fievez and Associates 55. Right rotations for TopCrop, Daniel Fels, Agriculture Western Australia 56. Dollars of water use efficiency, Andrew Rintoul, FAST National, GRDC funded project, Planfarm 57. Farm business structures, Andrew Rintoul, FAST National, GRDC funded project, Planfarm CLIMATE 58. Broadscale weather aspects affecting Western Australia during 1998 and prospects for 1999, Mal Lamond, Lamond Weather Services 59. An updated look at aspects of rainfall trends and variability in the south-west of Western Australia, Roger Tapp, Climate and Consultancy Section, Bureau of Meteorology, Perth WA 60. Frost research in the eastern wheatbelt, Craig White, Research Officer, Agriculture Western Australia, Presented by D.G. Abrech